The invention relates to powdering, and in particular to a powdering system, and more particularly it relates to a method and to a device enabling a film of powder to be formed on the surface of a part, the film being continuous and substantially uniform.
An example of a use for the invention lies in forming a deposit of a developer in powder form on the surfaces of parts in an installation for detecting any open defects that might be present in the surfaces of parts under inspection, in particular metal parts that might present surface defects in the form of fissures or cracks. In certain installations, a penetrating composition including an indicator substance is applied to the surfaces of the parts for inspection. After the surfaces have been washed and dried, a developer in powder form, such as talc, is deposited on the surfaces of the part in order to cause the indictor substance that has penetrated into any defects and that has therefore not been eliminated by washing, to be extracted from those defects by capillarity. The indicator substance is typically a colored or fluorescent compound that shines under ultraviolet (UV) illumination, thereby providing an easily-visible indication that a defect is present.
The continuity, the regularity, and the uniformity of the deposit of the developer are parameters that have an influence on the quality of detection.
Patent document FR 2 163 182 describes a dispenser for measuring out a powder, the dispenser having a pierced tube that is fed with air under pressure and that passes through a fluidized bed of powder contained in a tank. The tube opens out into the top portion of the tank above the bed of powder, and a mixture of air and powder as ejected by the tube is taken up immediately on leaving the tube by an outlet pipe. Any clumps of powder grains entrained with the air traveling along the tube will therefore also be taken out.